6 Mader TH, Gibson CR, Pass AF. Regarding "Diurnal Pattern of Intraocular Pressure is Affected by Microgravity When Measured in Space With the Pressure Phosphene Tonometer." J Glaucoma. 2012 Apr 6. [Epub ahead of print]http://www.ncbi.nlm.nih.gov/pubmed/22495070 NOTE: This letter comments on a specific point in an earlier article with the above title (PMID: 21968970). The letter is temporarily available online without charge: http://dx.doi.org/10.1097/IJG.0b013e318252d5af The response to this letter is below.